1. Field of the Invention
The present invention is directed to a heat moisture exchange device which is usable with a tracheotomy tube and a tracheotomy tube combined with a speaking valve.
Tracheotomy is a surgical procedure which is frequently performed to relieve obstruction of airflow through the larynx and upper trachea. One of its main side effects is loss of essential breathing functions including humidification, warming and filtering of air, coughing, smelling, tasting, swallowing, and more devastatingly, speaking. In tracheotomy patients, because inhaled air enters the trachea directly, it is very important for health reasons and for the patient's comfort, that the inhaled air is at substantially the same temperature and contains the same quantities of moisture and dust as if it had reached the trachea after passing through the upper airway (nostrils, nose, pharynx and larynx), meaning a temperature approaching 32° Celsius with a moisture content approaching saturation at the temperature of this air and substantially free of dust. HME's (Heat Moisture Exchanger) enable this result to be achieved to some degree; the filter mass blocks a major part of the dust in suspension in the air, of course, the water vapor contained in the patient's exhaled air, which is saturated at the temperature of the organism, condenses on the filter mass which is therefore heated substantially to the body temperature; inhaled air, arriving at the temperature of the ambient air, is warmed and takes up moisture in contact with the filter mass which is at a higher temperature and contains the condensed water before traveling into the patient's lungs with inhalation.
In order to overcome these undesirable side effects of a tracheotomy procedure, the passive HME was developed and has been available for many years. An HME consists of a housing to direct exhaled airflow from the patient, through one of many types of humidifying and moisturizing media. This device is placed externally in between the outside air and the patient's air intake at the tracheotomy tube. Exhaled air from the patient enters the HME, is directed across the media. The media serves to absorb and retain moisture from the exhaled air. On inspiration, humidified and warmed air is then breathed in by the patient, thus achieving some of the effect of the natural nasal passage. The ebb and flow of air across its surface allows a recurring transference of moisture from the patient's exhaled air to the HME and back to the patient. The HME's hence provide humidification warming and filtration of air that the tracheotomy patients breathe. The problem with the current HME's on the market is that because air flow inside them is linear, the exchange of humidity and warmth of the air that flows through the HME is not very efficient, hence a relatively large amount of HME foam material is needed, hence making the device quite bulky and unattractive to the patient. The present invention introduces a novel type of HME having a shape which is compact and designed to redirect airflow inside the HME in a turbulent fashion, hence enhancing the efficiency of humidification, warming and filtration of air.
Another problem is that because HME's moisturize and filter exhaled air, there is no one HME that can work with the speaking valves that are currently on the market because the valves are closed upon exhalation and do not allow air to pass. This invention addresses this issue and solves this problem by introducing an HME that works in combination with a speaking valve to allow both air moisturizing AND speech.
One additional significant situation that tracheotomy patients face is loss of speech. When a tracheotomy is present, exhaled air follows the path of least resistance, and goes through the tube, limiting the vibratory movement of the vocal cords, and hence limiting perceptual speech. This creates a psychological hardship, as communication is critical to patients' overall medical care and social interactions. This problem can be particularly disruptive in children, where tracheotomy can actually impact the development of normal language skills. In order to redirect the air through the vocal cords, the patient may use a finger to occlude the tracheotomy tube. Finger occlusion however has several limitations: it requires manual dexterity (which some patients may lack); it also requires coordination of phonation with breathing (which some patients may be unable to perform); and it is unsanitary. The use of a tracheotomy speaking valve enables tracheotomy patients to speak without having to occlude the tracheotomy tube with their finger. Unidirectional speaking valves have a displaceable element that allows air to flow through the cannula and into the lungs during inspiration and prevent air from flowing through the cannula during exhalation. Thus, during expiration, air flows through the patient's upper airways, such as the sub-glottic trachea, larynx, pharynx, mouth and nasal passages. As a result, unidirectional speaking valves allow tracheotomy individuals to communicate orally and maintain clear upper airway passages by coughing or expelling air through the upper airway passages.
The problem is that there is no one speaking valve currently on the market that can be used in combination with an HME's, the patient who use these speaking valves are unable to humidify/warm and filter the air that they inhale. This is due to the fact that the current speaking valves on the market are “biased closed”, which means that, while they allow redirection of air towards the larynx during exhalation (and subsequent speech), they do NOT allow exhaled air to flow through the valve. This limitation places the tracheotomy patient in the unfortunate position of being able to speak with a speaking valve, but not being able to use an HME in order to humidify/warm and purify the breathed air. The object of this invention is to introduce an HME that can function in combination with a speaking valve and humidify/warm and purify the air that a tracheotomy patient breathes.
In the parent application, we have previously described a speaking valve with a ball that moves inside a chamber where eccentrically positioned ramps act as a stop mechanism and also act as a dynamic guide that directs the ball towards the front or the back of the chamber. The patient can vary the position of the valve (valve “up” or valve “down”) by rotating it 180° up or down, and this allows the ball to be seated in the proximal part of the chamber either in the “biased open” or biased closed” position. This feature gives the patient control on the use of the valve to preferentially allow the exhaled air to escape through the proximal opening or redirect the air towards the larynx and speak.
The current invention is a continuation in part of the previous invention, extending the functionality of our previously described dynamic speaking (valve “up” or valve “down”) (which allows “biased open” or “biased closed” usage) to be able to combine it with an HME for the sake of speech AND humidification, warming, and filtration of air.
2. Description of Related Art
A variety of one-way speaking valves has been described in the literature and is on the market. These include the Passy-Muir valve, the Shiley Phonate valve, the Kistner valve and the Montgomery speaking valve, and they operate via a flap or diaphragm. These “flapper” valves close on exhalation in order to provide speech; hence they cannot be used in combination with an HME. Prior U.S. Pat. No. 5,505,198 (Siebens et al) describes a unidirectional tracheotomy speaking valve with an external cylindrical housing chamber that contains a ball acting as the displaceable element. The ball moves back and forth during inspiration and expiration, and is limited from going beyond the housing chamber during inspiration by a pin or a wire that extends into the chamber and intersects a path of travel of the ball, preventing it from entering the patient's airway. In this patent, the housing chamber is external to the tracheotomy tube and attached to the cannula of a tracheotomy tube through coupling. U.S. Pat. No. 6,588,428 (Shikani et al) describes a similar design unidirectional speaking valve in which the housing chamber is internal and an integral part of the inner cannula of the tracheotomy tube, the ball is guided by longitudinal ribs and is restrained in the cannula by a wire.
While these ball valve patents constitute a substantial improvement in the art over the flapper valves, nevertheless, the fact that the valve housing chamber is a simple cylindrical tube that houses a ball that travels back and forth along the tube's central axis, with no guiding ribs that could potentially direct the movement of the ball depending on the orientation of the valve (valve “up” or “down”). This unidirectional ball speaking valve cannot be used in concert with an HME.